Converged Enhanced Ethernet (CEE) is the term used to describe a set of enhancements to Ethernet that are being developed within the industry and standards bodies. CEE will allow Ethernet to better handle different classes of traffic in the data center, as well as eliminating the risk of packet loss during transmission. These enhancements allow Ethernet to meet the needs not only of the existing Ethernet network portion of the data center but also the storage side by introducing a new protocol called the Fiber Channel over Ethernet (FCoE). FCoE can be deployed without disrupting the legacy Ethernet network. It supports I/O consolidation of Ethernet and storage traffic at the rack level, reducing the number of adapters, cables, switches and transceivers that each server must support, while protecting the investment in existing Ethernet infrastructure.
Even though Ethernet is the dominant data communications standard today, due to early limitations on storage networking in the Ethernet standard, Fiber Channel (FC) is the widely used protocol for storage area networks (SANs). Therefore, servers in the datacenter require connections to both Ethernet and FC networks where data must be ensured to flow seamlessly. The current practice in data centers enables this seamless flow by the use of separate adapter cards, cables and switches, all leading to increased costs. FCoE attempts to solve this problem by encapsulating FC frames within an Ethernet frame and hence defining a new FCoE frame type. This encapsulation is shown conceptually in FIG. 1. Converged traffic is supported between the servers (which have converged network adapters (CNAs)) and an FCoE switch, and separated out on the uplink side of the switch to either the Ethernet or storage areas of the data center.
The current state of the art in these types of deployment are point-to-point connections between the servers and the FCoE switch using small form-factor pluggable plus (SFP+) copper interconnects predominantly in a top-of-rack (TOR) configuration, though end-of-row (FOR), and/or middle-of-row (MOR) configurations are utilized in the data center. The reason these copper cables are used in a point to point fashion has to do with the required electrical performance. The cables could not meet these performance requirements if they were used in a structured cabling environment (where the passive patch panels would be used). Although structured cabling is greatly preferred over point to point configurations, these performance requirements are a barrier to the adoption of structured cabling. Additionally, due to cable reach limitations of SFP+ copper interconnects (˜7-10 m for passive cables and possibly up to 20 m for active cables), these configurations limit the reach of EOR/TOR/MOR deployment, forcing the addition of more switches. There are no solutions available in the market today to extend the reaches of SFP+ copper interconnects either in point-to-point or point-to-multipoint connections without the use of switches. Switches are relatively expensive hardware; further, installation labor costs, and also extensive reconfiguration (moves, adds and changes: MACs) labor costs add to the overall expense.
In high performance network applications (e.g., 10 Gbps (gigabit per second) Ethernet), SFP+ style connectivity is preferred due to its small form factor allowing high density port switches to be implemented. It is preferred over 10 G BASE-T media primarily because of the power dissipation required for this style media and associated latency. It is also preferred over other 10 Gbps implementations that rely on parallel transmission such as CX4, InfiniBand, or PCI Express. SFP+ connectivity employs a serial transmission of 10 Gbps which requires many fewer I/O pins and thereby allows for greater density in connected hardware. Previously, only optical based SFP+ connectivity has been used. Recently copper-based SFP+ connectivity has been of interest due to the low cost of this media type, and because it utilizes the same mechanical interface as the optical SFP+ interface. A disadvantage of copper-based SFP+ media is the cable length limitation. The cable length limit is on the order of approximately 7-10 m for a passive cable. Systems require that some interconnects go beyond 10 m, and this causes a problem for SFP+ copper based media implementation.
Corresponding reference characters indicate corresponding parts throughout the several views. The examples set out herein illustrate embodiments of the invention, and such examples are not to be construed as limiting the scope of the invention in any manner.